Carbohydrate-deficient transferrin: Validity of a new alcohol biomarker in a sample of patients with diabetes and hypertension

Objective: To test the reliability and validity of a new alcohol biomarker. Design: Cross-sectional with matched control. Alcohol use, symptoms of alcohol dependence, health status, current medications, carbohydrate-deficient transferrin (CDT) levels, and gamma-glutamyl transferase levels were assessed. Validity of the %CDT test was estimated using a drinking cutoff of 90 or more drinks in the previous 30 days. Participants: Sample (n = 799) included 89 patients with type 2 diabetes, 299 patients with hypertension, 209 patients with hypertension and type 2 diabetes, and 202 matched control subjects with neither diabetes nor hypertension. Results: Three hundred ninety-six women and 403 men ages 30 to 60 participated in the study. Six percent ( 45 of 799) reported drinking more than 14 drinks per week, 2% (n = 17) met criteria for alcohol abuse, and 3% (n = 23) met DSM-IV criteria for dependence. The overall sensitivity of the %CDT test was 61% with a specificity of 85%. A receiver operating characteristic curve was used to determine that the best fit was for persons who reported >90 drinks per month and a CDT level >2.5% with an area under the curve of 0.83. Test-retest reliability (R) was 0.94. Conclusions: %CDT levels are useful in detecting and/or confirming high-risk drinking in patients being treated for type 2 diabetes and hypertension.